The present invention relates to the field of signal processing.
Signal processing in the general sense, is the manipulation of a signal to achieve a specific purpose. For example, the purpose of signal processing in radar and certain communication systems is to improve the signal-to-noise ratio and reject interference in the process of transforming a specific set of data. The types of processing algorithms include convolution, time and space integrating correlation, matched filtering and data compression. For programmability and accuracy, digital processing techniques are preferred over analog methods. However, for real time signal processing, analog components may be required for computer intensive operations.
Typically, the devices require the capability to operate at the systems intermediate frequency (IF) and have a wide bandwidth capability. The addition of programmability increases the effectiveness of the device to adapt to the system's operating environment.
Many forms of programmable broadband delay lines have been developed for analog signal processing. These include surface acoustic wave devices (SAW), integrated optic devices, fiber optic devices and acoustic charge transport (ACT) devices. The measure of a programmable delay lines performance is a function of the number of taps, the accuracy of tap weights, bandwidth, programming speed and size. The major limitation of SAW devices is the large number required to generate various waveforms. Individual SAW devices are switched in and out as required for the specific filtering operation. The integrated optic and fiber optic approaches provide a relatively short delay line namely 5 nsec/meter of fiber. Thus relatively large amounts of fiber are required for delay lines approaching 5 microseconds. The ACT devices provide wide bandwidth and have speed in a compact package. However the devices are currently limited to a tap accuracy of five bits.